IBM 5150 Technical Reference page 204

LaC OBJ
LINE SOURCE
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,...-.....
~
FE8F EBEA
FE91
FE91 FA
FE92 89166COO
FE96 890E6[00
FE9A C606700000
FE9F EBOA
FEAS
FEA5
FEA5 FB
FEA6 IE
FEA7 50
FEA6 52
FEA9 E69200
FEAC ff066COO
FEBO 7504
FEB2 ff066EOO
HB6
FEB6 833E6£0016
FEBB 7515
FEBD 613E6COOBOOO
FEC3 7500
FEes 2BCO
FEC7 A36EOO
FECA A36COO
FECD C606700001
FED2
FED2 FEOE4000
FED6 750B
FED6 60263FOOFO
FEDD BOOC
FEDF BAF203
FEE2 EE
FEf3
FEE3 CD1C
fEES B020
fEE7 E620
FEE9 SA
FEEA 56
FEEB IF
FEEC CF
FEED 31363031
FEFI 00
FEF2 OA
5941
5942
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J"P
T1 ; TOO_RETURN
T3:
; SET_TIME
Cll
; NO INTERRUPTS WHILE WRITING
t10V
TIMER_lOW.OX
I10V TIMER_HIGH.
ex
1 SET THE TIME
"OV
TIMER_OFl,O
; RESET OVERFLOW
J"P
T1
; TOO_RETURN
lIt'E_OF_DAY ENDP
1-----------------------------------------------------.-­
; THIS ROUTINE HANDLES THE TINER INTERRUPT FROtt
CHANNEL 0 OF THE 8253 TIMER. INPUT FREQUENCY
IS 1.19318 MHZ AND THE DIVISOR IS 65536, RESULTIHG
I
IN APPROX. 18.2 INTERRUPTS EVERY SECOND.
j
THE INTERRUPT HANDLER MAINTAINS A COUNT OF INTERRUPTS:
;
SINCE POWER ON TItlE. WHICH MAY BE USED TO ESTABLISH
; TIME OF DAY.
I THE
INTERRUPT
HANDLER ALSO DECREMENTS THE MOTOR
CONTROL COUNT OF THE DISKETTE. AND WHEN IT EXPIRES.
; WILL TURN Off THE DISKETTE MOTOR
f
AND RESET THE
;
MOTOR RUNNING FLAGS.
; THE INTERRUPT HANDLER WILL ALSO INVOKE A USER ROUTINE:
I
THROUGH INTERRUPT 1 CH AT EVERY TIME TICK. THE USER
,
J
I'lJST CODE A ROUTINE AND PLACE THE CORRECT ADDRESS IN :
; THE VECTOR TABLE.
i ---------------­ -------------­ -------­ ----------­ - -----­
ORG
OFEA5H
TIMER_INT
"OC
FAR
STI
INTERRUPTS BACK ON
PUSH OS
PUSH
AX
PUSH OX J SAVE MACHINE STATE
CAll
DDS
INC TIMER_LOW ; INCREMENT TIME
JNZ
T4
j
TEST_DAY
INC TIMER_HIGH
; INCREMENT HIGH WORD OF TIME
T4: ; TEST_DAY
CMP TIMER_HIGH.016H ; TEST FOR COlINT EQUALING 24 HIXJRS
JNZ T5 J DISKETTE_CTl
C"P
TIMER_LOW.OBOH
JNZ T5 ; DISKETTE_CTl
1------ TIMER HAS GONE 24 HOURS
SUB
AX,AX
MOV TIMER_HIGH .AX
"OV
TIMER_LOW.. AX
"OV
TIMER_OFL .1
;------ TEST FOR DISKETTE TIME OUT
TS:
• DISKETTE_CTl
DEC MOTOR_COUNT
JHZ T6 J
RETURN IF COUNT NOT OUT
AND
MOTOR_STATlJS.OFOH J TURN OFF MOTOR RUNNING BITS
I10V AL.OCH
MOV OX,03F2H ; FDC CTl PORT
OUT DX.AL
, TURN OfF THE MOTOR
T6: ; TIMER_RET:
INT
IC"
I TRANSFER CONTROL TO A USER ROUTINE
"OV
Al,EOI
OUT 020H .Al ; ENO OF INTERRUPT TO 8259
POP OX
POP AX
POP
OS
j
RESET MACH INE STATE
IRET , RETI..IRN FROM INTERRUPT
TIMER_INT
ENDP
"0
OB
'1601' .13.10
6011
6012
6013
6014
6015
;
­
------------------­---------­---------------------------------­
THESE ARE THE VECTORS WHICH ARE MOVED INTO
THE 6086 INTERRUPT AREA DURING POIolER ON.
ONLY THE OFFSETS ARE DISPLAYED HERE. CODE SEGMENT
System BIOS 5-111